Thank you very much.
It works.
On Thu, Nov 18, 2010 at 8:17 PM, Karl Phillip <maxp...@gmail.com> wrote:
> Try this:
> *primary_surface->SetBlittingFlags(primary_surface,
> DSBLIT_BLEND_ALPHACHANNEL);*
>
> You might have to remove the calls to SetSrcBlendFunction() and
> SetDstBlendFunction().
>
> []'s
>
> On Thu, Nov 18, 2010 at 5:22 AM, Kelvin Chen <ryu...@gmail.com> wrote:
>
>> Hi, all:
>>
>> How can I make IDirectFBSurface::blit supporting a transparent background?
>> I have tried a lot of methods, but it doesn't work.
>>
>> Here is my problem.
>> 1> draw something to the primary_surface
>> 2> create a tempory_surface with transparent background and draw something
>> to it
>> 3> blit the content of temporary_surface to the pramary_surface, but this
>> operation should not erase what primary_surface already have
>>
>> Here is my code, it doesn't work, I don't know why. The blue rectangle
>> draw on the primary_surface will be erased after the blit operation.
>>
>> Thanks a lot!
>>
>> #include <iostream>
>> #include <directfb.h>
>>
>> *using* *namespace* std;
>>
>> *int* main(*int* argc, *char* *argv[])
>>
>> {
>> IDirectFB *dfb;
>>
>> // Initialize DirectFB
>> DirectFBInit(&argc, &argv);
>> DirectFBCreate(&dfb);
>> dfb->SetCooperativeLevel(dfb, DFSCL_FULLSCREEN);
>>
>>
>>
>> // Create primary surface
>> IDirectFBSurface *primary_surface;
>> DFBSurfaceDescription primary_surface_description;
>> primary_surface_description.flags =
>> DFBSurfaceDescriptionFlags(DSDESC_CAPS | DSDESC_WIDTH | DSDESC_HEIGHT |
>> DSDESC_PIXELFORMAT);
>>
>>
>> primary_surface_description.caps = DFBSurfaceCapabilities(DSCAPS_PRIMARY
>> | DSCAPS_FLIPPING);
>> primary_surface_description.pixelformat = DSPF_ARGB;
>> primary_surface_description.width = 1280;
>> primary_surface_description.height = 800;
>>
>>
>> dfb->CreateSurface(dfb, &primary_surface_description, &primary_surface);
>> // Draw a big blue square
>> primary_surface->SetColor(primary_surface, 0x00, 0x00, 0xff, 0xff);
>>
>>
>> primary_surface->FillRectangle(primary_surface, 50, 50, 600, 600);
>> primary_surface->Flip(primary_surface, NULL, DFBSurfaceFlipFlags(0));
>> // Sleep 1 seconds to observe the result
>>
>>
>> sleep(1);
>>
>> // Create temporary surface
>> IDirectFBSurface *temporary_surface;
>> DFBSurfaceDescription temporary_surface_description;
>> temporary_surface_description.flags =
>> DFBSurfaceDescriptionFlags(DSDESC_CAPS | DSDESC_WIDTH | DSDESC_HEIGHT |
>> DSDESC_PIXELFORMAT);
>>
>>
>> temporary_surface_description.caps =
>> DFBSurfaceCapabilities(DSCAPS_FLIPPING); // Not primary
>> temporary_surface_description.pixelformat = DSPF_ARGB;
>> temporary_surface_description.width = 1280;
>>
>>
>> temporary_surface_description.height = 800;
>> dfb->CreateSurface(dfb, &temporary_surface_description,
>> &temporary_surface);
>> // Clear the background with transparent black
>>
>>
>> temporary_surface->Clear(temporary_surface, 0, 0, 0, 0);
>> temporary_surface->SetColor(temporary_surface, 0, 0, 0, 0);
>> temporary_surface->FillRectangle(temporary_surface, 0, 0, 1280, 800);
>>
>>
>> // Draw a small red square
>> temporary_surface->SetColor(temporary_surface, 0xff, 0x00, 0x00, 0xff);
>> temporary_surface->FillRectangle(temporary_surface, 0, 0, 200, 200);
>>
>>
>> temporary_surface->Flip(temporary_surface, NULL, DFBSurfaceFlipFlags(0));
>> // Copy the content of the temporary surface to primary surface
>> DFBRectangle rect;
>> rect.x = 0;
>>
>>
>> rect.y = 0;
>> rect.w = 1280;
>> rect.h = 800;
>> temporary_surface->SetSrcBlendFunction(temporary_surface, DSBF_SRCALPHA);
>> primary_surface->SetDstBlendFunction(primary_surface, DSBF_DESTALPHA);
>>
>>
>> primary_surface->Blit(primary_surface, temporary_surface, &rect, 0, 0);
>> primary_surface->Flip(primary_surface, NULL, DFBSurfaceFlipFlags(0));
>> // Sleep 3 seconds to observe the result
>>
>>
>> // Note that the original blue square is not destroyed
>> sleep(3);
>>
>> temporary_surface->Release(temporary_surface);
>> primary_surface->Release(primary_surface);
>>
>>
>> dfb->Release(dfb);
>>
>> *return* 0;
>> }
>>
>>
>>
>>
>> --
>> Kelvin Chen
>>
>> _______________________________________________
>> directfb-users mailing list
>> directfb-users@directfb.org
>> http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-users
>>
>>
>
--
Kelvin Chen
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